1. Field of the Invention
The present invention relates to a headbox of a paper machine or a cardboard machine having a plurality of devices positioned across a machine width for sectionally influencing a characteristic of the pulp suspension; to an apparatus for influencing a cross-section profile of a headbox having a device transversely positioned across a machine width for distributing a fluid, at least one connecting opening transversely positioned across the machine width between the fluid distributing device and an inner chamber of the head box, and a plurality of devices that sectionally influence a pulp suspension characteristic; and to a process for determining the position and width of the sections of a headbox.
2. Discussion of Background Information
Headboxes with devices for the sectional influencing of a characteristic of the pulp suspension are generally known in the art. German Patent Application No. DE 37 41 603, for example, describes a headbox arrangement in which a diluting fluid is supplied to the headbox in a vicinity of a compensation channel located between two turbulence generators. The dilution fluid is supplied through supply points that are uniformly distributed across a width of the headbox, and the single supply amounts can be adjusted individually.
Another possibility for influencing a characteristic of the pulp suspension is discussed in German Patent Application No. DE 40 19 593. This document describes a headbox that exhibits a uniformly distributed sectioning and that enables varying of the pulp concentration sectionally and/or the pulp suspension amount per section.
Common to the headboxes described above is that the devices that cause the sectioning of the headbox are uniformly distributed across a width of the headbox and are fixed in their positions. In this manner, the headboxes of the prior art have permanently adjusted sections in which a width of individual sections is permanently defined. This embodiment of the headbox, and, in particular, the sectioning of the headbox, provides the advantage that an inexpensive manufacture of the headbox is possible and that the regulation tasks arising during the influencing of the characteristics of the pulp suspension, can be easily solved.
However, a problem of the prior art headboxes lies in that characteristic alterations of the pulp suspension, as observed across the width of the headbox, are not equally large at all points, i.e., there are regions in the headbox, e.g., the peripheral regions, in which relatively large characteristic alterations occur, while there are other regions in which only very minor characteristic alterations of the pulp suspension from the ideal condition occur. Thus, it was necessary in the prior art to keep a section width as small as possible, so that an alteration of the characteristics did not become too large across a section. This requires that the number of sections sharply increases with the desired refinement of the adjustment possibilities and likewise increases the costs of production enormously.